Whistle



Sept. 17, 1963 P. w. TAPPAN ETAL 3,103,911

WHISTLE Filed March 4, 1960 2 Sheets-$heet 1 dz-zw/ ajgg Sept. 17, 1963 Filed March 4, 1960 P. W. TAPPAN ETAL WHISTLE 2 Sheets-Sheet 2 co ureoutn DEV/CE PASS BA/V0 p e i ezr m m' United States Patent 3,103,911 WHESTLE Peter W. Tappan, Bartlett, Arthur C. Vaccaro, Chicago, and Bernard R. Knhl, Arlington Hei hts, Iih, assignors to Warwick Manufacturing Corporation, a corporation of Delaware Filed Mar. 4, 19616, Ser. No. 12,862 6 Claims. (Cl. 116137) This invention relates to a remote control signalling systlem utilizing an ultrasonic whistle and to the whistle itse f.

Short range remote control systems, as for the remote control of a television receiver, are known, in which an electrical generator or a mechanical vibratory device is used for signalling. There are two systems presently in rather wide use for such control, one utilizing a radio Wave transmitter and the other ultrasonic mechanical vibrators. -Both are expensive and the radio wave system requires a source of power, as batteries, at the remote unit. A whistle in which an air column is excited, as an organ pipe type whistle, disclosed herein provides an inexpensive and reliable control and signalling system. Certain characteristics of the whistle, as the radiation pattern of the wave generated and the relation of frequency of the generated signal to the exciting pressure are utilized in providing a satisfactory remote signalling device.

One feature of the invention is a signalling system including an air actuated whistle, a manually actuable means connected with the whistle and delivering air at varying pressures to the whistle, the whistle having a signal frequency which varies with pressure, and a receiver having a pass band lying within the range of frequencies of the whistle signal.

Another feature is the provision of a whistle having a tubular body, a plug in one end of the body, a palate in the other end and spaced from the plug, the body having a notch formed therein between the plug and the palate, with one notch surface being at a right angle to the axis of the tubular body and the other notch surface being at an angle of the order of 30 with respect to the body axis. A further feature is that the palate has a surface spaced from the other wall of the tubular body, the spacing being of the order of /s to /3 the inner diameter of the body.

Yet another feature is that certain critical dimensions of the whistle, as the inner diameter of the whistle body, and in some cases the length of the plug are such as to prevent any resonant modes of vibration except the desired air column resonance, at the frequency of operation of the whistle. This prevents spurious vibrations that would reduce the output of the whistle.

Still a further feature is the combination of a whistle having a vibration radiating surface with a reflector having a focal point, the whistle being mounted adjacent the reflector with a point on the radiating surface being substantially at the focal point of the surface. Another feature is that the radiation from the whistle is in a narrow fan-shaped band and the reflector has a parabolic surface which intercepts the radiation from the whistle and has generally straight sides in planes parallel with the major direction of radiation from the whistle. And a further feature is that the whistle is mounted in a reflector and a whistle guard extends across the reflector in an area outside the major area of radiation from the whistle.

Another feature is the combination in a whistle of a collapsible bulb having a single opening therein, a whistle holder carried on the bulb and having an air inlet passage therethrough communicating with the opening in the bulb and a whistle carried with a holder and communicating ice with the opening in the bulb. A check valve is provided in the inlet passage and preferably held therein by a retainer plate which has tab portions that engage a neck defining the opening in the bulb, securing the bulb and whistle holder together. And a further feature is that the whistle holder has a skirt portion which telescopes with the shoulder of the bulb so that the parts do not separate upon deformation of the bulb.

Further objects and advantages will become apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIGURE 1 is a plan view of a signalling device embodying the invention;

FIGURE 2 is a side view thereof;

FIGURE 3 is an end view thereof looking from the right of FIGURE 1;

FIGURE 4 is an enlarged fragmentary section taken generally along line 44 of FIGURE 3;

FIGURE 5 is an enlarged fragmentary section taken generally along line 5-5 of FIGURE 3;

FIGURE 6 is an enlarged fragmentary section through the whistle;

'FIGURE 7 is a fragmentary view taken as indicated by a line 77 of FIGURE 4;

FIGURE 8 is a curve illustrating the variations of the frequency and amplitude of the generated signal as a function of pressure; and

FIGURE 9 is a block diagram of a receiving system.

While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail an embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

The short range remote control system with which the present invention is concerned is particularly suited for control of a television receiver or the like, within a range of about 25 or 30 feet.

Turning now to the drawings, in the preferred embodi me-nt of the invention illustrated, a manually actuable, collapsible bulb 15, as of a soft rubber material, has an elliptical whistle holder 16 mounted at one end and carrying a whistle 17. Compression bulb 15 has a single opening 18 formed at one end thereof and which receives a centrally located extension or boss 19 on whistle holder 16. Whistle 17, of the vibrating air column or organ pipe type, is received in a centrally located passage 21) through extension 19 of the whistle holder. Surface 22 of the whistle holder forms a reflector associated with whistle 17, as will be described, to concentrate and direct the generated waves. An air inlet passage 23 is formed through boss 19 of the whistle holder, opening at 23a through the reflector surface and at an opposite end having a shoulder 23b in a valve cavity 230 receiving an inwardly opening check valve 24 therein. Upon compression of bulb 15, valve 24 closes against shoulder 23b and air is forced under pressure through whistle 17, sounding it. Upon release of the compression bulb it returns to its original shape, valve 24 opening to permit free inward passage of air.

The frequency of the Whistle is preferably in the ultrasonic range, as of the order of 35,000 to 45,000 cycles per second, to prevent accidental actuation of the receiving circuitry by extraneous noises which are principally in the audible range. FIGURE 8 shows graphically the qualitative relationships between the pressure applied to the whistle by manipulation of the compression bulb and the frequency and amplitude of the generated ultrasonic signal. The frequency has a substantially straight line relationship with the pressure, increasing linearly as the pressure increases. The amplitude is relatively constant in a band from pressure P to P although it exhibits a slight increase with increasing pressure before it falls off above P The usable output of the whistle is generally between the pressures P and P corresponding with frequency range from f to f When the bulb '15 is manually compressed, the pressure builds up at a rate depending upon the rapidity with which compression is effected and then decreases as the air in the bulb is exhausted through the whistle. The increase and decrease in pressure causes the whistle frequency to sweep twice through the band of frequencies, first increasing and then decreasing. This characteristic of the whistle is utilized in the design of the receiving system to eliminate either sensitive calibration of the system or the use of broad band high gain amplifiers which are subject to noise interference.

FIGURE 9 illustrates the receiver in block diagram form including a pickup device or microphone 28, an amplifier 29 and a controlled device 30. The controlled device is of any suitable type, for example, a motor controlling the channel selector of a television receiver. Amplifier 29 has a relatively narrow pass band as indicated in the drawing so that it may provide the required amplification without undesirable expensive components or unnecessary noise interference. The pass band in the amplifier is located between the frequencies f and f the lower and upper useful limits of the whistle, the system relying upon the pressure frequency characteristics of the whistle to deliver a signal which will be received and passed by the amplifier upon manipulation of the compression bulb. Neither the frequency of the whistle nor the frequency of the amplifier pass band are critical so long as the amplifier pass band lies within the band of frequencies generated upon actuation of the whistle.

The construction of whistle 17 is best seen in FIGURE 6. A tubular body 33 has a bore 33a with an inlet end 33b through which actuating air pressure is applied to the whistle, and a centrally located notch 34 formed therein. A palate 35 is carried in the tubular body inlet end. A frequency adjusting plug 36 is received in the bore 33a of the tube and is carried by a threaded shank 37 terminating in a slotted head 38, the distance between outer face 35a of the palate and the inner face 36a of the plug being the principal frequency determining dimension.

Notch 34 is formed by two surfaces 34a and 3417, with surface 34a extending generally at right angles to the axis of tubular whistle body 33 and aligned with the outer face 35:: of the palate. Surface 34b has an angle of the order of 30 with the axis of the tubular whistle body, this angle having been found to provide the maximum reliable amplitude of whistle signal. The depth of notch 34, again for maximum amplitude and reliability of the whistle output, should be of the order of /2 the diameter of the whistle body. In other words, the line of intersection between surfaces 34a and 34b forms a diametcr of the whistle body.

Palate 35 has a planar preferably fiat surface 38a spaced from the inner surface 39 of the whistle body bore 33a forming an air passage which opens into notch 34. Flat surface 38a is preferably parallel with the bottom of notch 34, i.e., the line of intersection between notch surfaces 34a and 34b. The spacing between inner surface 39 and palate surface 38a has an effect on the amplitude of the generated ultrasonic signal and it has been found that this spacing or throat size should be in the range of to A the inner diameter of the whistle body. It is preferable that the dimension be held close to /5 the body diameter to reduce the rate of dissipation of the air held under pressure in the bulb 15, while maintaining the maximum amplitude of the whistle signal.

The nominal frequency of the whistle is determined primarily by the length of the vibrating air column or the distance between the face 35a of the palate and the inner end of adjusting plug 36. To avoid spurious vibrations in the whistle and the resulting undesired dissipation of energy there are several further dimensional relationships which should be observed. The inner diameter at surface 39 of the tubular whistle body 33 should be a value that will not permit additional resonant modes of air vibration within the whistle at the nominal whistle frequency. The undesired resonant mode of air vibration most likely to occur is radial or transverse to the axis of the whistle body. Radial or diametric resonance may be avoided by selecting a diameter other than an inte ral multiple of one-half wavelength within the frequency range of the whistle. However, if the diameter is greater than one-half wavelength, other modes of resonance may occur and it is preferable that the diameter be less than one-half wavelength at the highest frequency in the whistle range to avoid this possibility. The velocity of the confined sound waves is related to the geometry of the whistle and the one-half wavelength dimension may be slightly greater than one-half wavelength in free air.

Resonant modes in the solid portions of the whistle should also be prevented, by appropriate choice of the materials and dimensions of the tubular body 33, palate 35, and plug 36 and the method of mounting the whistle. If plug 36 or its end portion adjacent inner face 36a does not have a tight fit with body 33, longitudinal vibrations may occur in it in various modes. If it does have a tight fit, the entire structure may have a resonant mode within the whistle frequency range. These relations are dependent on various physical properties of the whistle, including the plug and body configuration, the density and elasticity of the material, and the velocity of sound waves in the material, and are difficult to calculate accurately. Resonant vibrations of this type may be avoided by empirical design considerations.

The radiation pattern of the notched organ pipe type whistle has been investigated and it is found that the ultrasonic waves are generated principally along a sharp edge 39a at the intersection of notch surface 34b with the inner surface 39 of the whistle body and are directed primarily outwardly therefrom in a fan shape pattern as indicated by broken lines 4% in FIGURES 4 and 5. The direction of radiation is generally upwardly and outwardly from the notch as viewed in FIGURE 4. The nature of the radiation pattern facilitates the design of a suitable refiector for the whistle. The reflector surface 22 is generally that of a parabola of revolution about the axis on which the whistle 17 is located. The extent of the parabolic surface must be sutficient to intercept the generated sound waves as shown in FIGURE 4, and it is only that portion of the parabolic surface which intercepts the major portion of the generated signal which is important. The sides of the parabolic reflector are cut off by plane surfaces 42 and 43 parallel with the axis of the paraboloid and on either side of the radiation pattern. This permits a reduction in the size of the whistle holder and the elliptioal shape without impairing the operation of the device. It will be noted that the air inlet opening 23a formed in the reflector surface is located below whistle 17 outside the area of maximum signal. In order to obtain the maximum advantage of the reflector, the midpoint of the signal generating notch edge should be located at the focal point of the parabolic surface. In practice, the position of the whistle is adjusted axially in the whistle holder, for maximum signal intensity.

A whistle shield 44 is carried by whistle holder 16 and has an annular portion 45 surrounding reflector 22 and a cross arm 45!! bridging the reflector surface between the planar surfaces 42 and 43. An aperture 46 in the center of the cross arm provides access to whistle plug head 33. it will be noted that the cross arm 46 of the whistle shield lies outside the area of maximum intensity signal and have little or no masking effect.

The compression bulb 15 is provided with an outwardly extending neck portion 50 defining the single opening 18 of the bulb. This neck fits over and extends along boss portion 19 of whistle holder 16. Check valve ball 24, which seats on shoulder 23b in the air inlet passage 23, is held in the valve cavity 230 by a retainer plate 52 fitted to the inner end of boss 19. As best seen in FIG- URES 5 and 7, valve retainer plate 52 has a pair of ears or tabs 53 which extend forwardly along the surface of boss 19. These tabs serve the dual purpose of positioning valve plate 52 and engaging a shoulder 54 at the base of the neck 50 of the bulb, holding the bulb and whistle holder together.

A second shoulder 55 is formed in the end face of compression bulb 15 and receives a skirt 56 forming a part of the whistle holder. The shoulder 55 extends inwardly of the skirt 56 for a suflicient distance to prevent the bulb from pulling completely away from the whistle holder upon deformation.

We claim:

1. In an air whistle adapted to be used in a signalling system to actuate a receiver; a collapsible bulb adapted when squeezed to supply air to a whistle, said bulb having side walls terminating at one end in a substantially flat end wall, a single substantially centrally located opening in said end wall and an elongated outwardly extending neck portion on said Wall completely surrounding said opening and defining the same; a whistle holder carried on said bulb and positioned in said opening, said holder comprising an elongated cylindrical member adapted to lie in said opening in said bulb in a substantially air tight fit and to be gripped and supported by said neck portion, and a substantially centrally located whistle supporting bore in said holder and extending therethrou-gh; and a whistle carried on said whistle holder and positioned in said bore, said whistle comprising a whistle body including a tubular member having a slot therein and an air passage therethrough, an edge of said slot forming a vibration radiating surface, a palate located in said air passage adjacent one end of said member, and an adjusting plug located in the other end of said tubular member and adjustable with respect to said pal-ate to vary the irequency of said whistle.

2. The device of claim 1 wherein the palate in said whistle body has a surface spaced from the inner wall of said tubular member, the spacing between the surface and wall being of the order of one-fifth to one-third the inner diameter of said tubular member.

3. The device of claim 1 wherein said tubular member in said whistle has an inner diameter other than a multiple of a half wave length of a sound Wave at the frequency of the operation of the whistle.

4. The device of claim 1 wherein said whistle slot directs vibrations only in one direction from said vibration radiating surface on actuation of the whistle and said device includes a reflector having a parabolic surface adjacent said whistle, a portion of the parabolic surface intercepting the vibrations radiating from the slot of the whistle, said reflector having generally planar sides parallel with the major direction of radiation from the whistle.

5. The device of claim 4 including a whistle guard outwardly of said whistle and extending across said reflector in an area outside the major area of radiation from said whistle.

6. The device of claim 1 wherein said bulb includes a shoulder formed in its surface and surrounding said opening and said whistle hoder includes a skirt portion which telescopes with the shoulder of said bulb.

References Cited in the file of this patent UNITED STATES PATENTS 457,259 Decoeur Apr. 4, 1891 1,272,822 Lund July 16, 1918 1,796,887 Cr-itchfield Mar. 17, 1931 2,238,668 Wellenstein Apr. 15, 1941 2,245,484 Leavens June 10, 1941 2,594,013 Hahn Apr. 22, 1952 2,920,604 McDonald Jan. 12, 1960 2,923,918 Adler Feb. 2, 1960 2,971,491 Yea ghey Feb. 14, 1961 3,028,582 Carlson Apr. 3, 1962 FOREIGN PATENTS 696,210 Germany Sept. 14, 1940 1,139,052 France June 25, 1957 

1. IN AN AIR WHISTLE ADAPTED TO BE USED IN A SIGNALLING SYSTEM TO ACTUATE A RECEIVER; A COLLAPSIBLE BULB ADAPTED WHEN SQUEEZED TO SUPPLY AIR TO A WHISTLE, SAID BULB HAVING SIDE WALLS TERMINATING AT ONE END IN A SUBSTANTIALLY FLAT END WALL, A SINGLE SUBSTANTIALLY CENTRALLY LOCATED OPENING IN SAID END WALL AND AN ELONGATED OUTWARDLY EXTENDING NECK PORTION ON SAID WALL COMPLETELY SURROUNDING SAID OPENING AND DEFINING THE SAME; A WHISTLE HOLDER CARRIED ON SAID BULB AND POSITIONED IN SAID OPENING, SAID HOLDER COMPRISING AN ELONGATED CYLINDRICAL MEMBER ADAPTED TO LIE IN SAID OPENING IN SAID BULB IN A SUBSTANTIALLY AIR TIGHT FIT AND TO BE GRIPPED AND SUPPORTED BY SAID NECK PORTION, AND A SUBSTANTIALLY CENTRALLY LOCATED WHISTLE SUPPORTING BORE IN SAID HOLDER AND EXTENDING THERETHROUGH; AND A WHISTLE CARRIED ON SAID WHISTLE HOLDER AND POSITIONED IN 